The present invention relates generally to Li-ion and/or Li-ion polymer batteries, and more particularly, to battery leads for use in a multi-layer cell, and a method of forming the same.
A Li-ion and/or Li-ion polymer battery is generally comprised of a plurality of layered sections, namely, an anode section, a cathode section and a separator layer that is disposed between the anode section and cathode section. Multi-layered battery cells are comprised of a plurality of anode sections and cathode sections.
Each anode section and each cathode section includes a layer of a conductive material that is disposed within or in contact with such section. This layer forms what is conventionally referred to as a xe2x80x9ccurrent collector.xe2x80x9d It is conventionally known to use metal screens or meshes or foils to form the aforementioned current collectors. Typically, copper mesh is used to form an anode current collector, and an aluminum metal mesh is used to form a cathode current collector. Multi-layer battery cells typically include a plurality of anode current collectors and a plurality of cathode current collectors. Each current collector generally includes an outwardly extending, short tab that is ultimately to be connected to a battery lead. It is, therefore, necessary to join all anode current collectors together and attach them to a single anode battery lead, and to join all cathode current collector tabs together and attach them to a cathode battery lead.
The anode and cathode battery leads are typically comprised of a flat, metallic strip, formed of copper, aluminum or nickel. The battery leads are typically formed from a generally continuous metallic strip having a width equal to the desired width of the battery lead. A length of the metallic strip, equal to the desired length of the battery lead, is then cut from a metallic strip. Typically, a portion of the battery lead undergoes a surface treatment, such as a cleaning and/or a roughening treatment in the area where the lead will extend through a battery package. This treated area increases adhesion and helps to form a seal around the battery lead where it extends through a battery package.
Sealing around a conventional battery lead is problematic because the battery lead is generally rectangular in cross-section. When pressed between two sheets of a packaging laminate, gaps or openings may be formed along the lateral edges of the lead preventing complete sealing of the battery assembly within the packaging.
It is known to wrap each battery lead with an adhesive/sealant material that more easily conforms around the lead when heated and pressed between a packaging laminate. Even with the addition of an adhesive/sealant band, the surfaces of the battery lead undergo treatment to promote adhesion to an adjacent surrounding material. In this respect, each battery lead typically undergoes one or more surface treatments along a portion thereof to enhance adhesion between the battery lead and a surrounding material that forms a seal around the battery lead where the battery lead projects through a packaging laminate. Performing these treatment processes on each individual lead is time-consuming and costly.
The present invention overcomes these and other problems and provides a method of forming battery leads from metallic sheet, wherein surface treatments on the battery lead are performed prior to severing a battery lead from the metallic sheet.
In accordance with a preferred embodiment of the present invention, there is provided a method of forming battery leads, comprising the steps of:
forming a plurality of aligned, spaced-apart elongated openings in a rectangular, metallic sheet, the metallic sheet having side edges and a width between the side edges equal to a desired length of a battery lead, the openings extending between the side edges and being aligned in a row that extends parallel to the side edges;
treating areas of the surfaces of the metallic sheet between the openings to enhance the adhesive properties thereof;
applying a strip of an adhesive/sealant material to each side of the metallic strip over the surfaces and the slots; and
cutting a battery lead from the metallic sheet by cutting the metallic sheet widthwise through each opening from one side edge to the other side edge.
In accordance with another aspect of the present invention, there is provided a battery lead, comprised of a thin, elongated, rectangular strip of a metal selected from the group consisting of copper, aluminum and nickel. A band of an adhesive/sealant material surrounds a portion of the strip. The strip has knife-like edges where the adhesive/sealant material surrounds the strip.
It is another object of the present invention to provide a battery lead for Li-ion and/or Li-ion polymer batteries.
It is another object of the present invention to provide a method of forming a battery lead for Li-ion and/or Li-ion polymer batteries.
It is another object of the present invention to provide a method of forming a battery lead as described, wherein the battery lead is generally a flat, rectangular strip that is cut widthwise from a metallic sheet.
A still further object of the present invention is to provide a method of forming a battery lead as described above that includes a process for shaping the edges of the battery lead to facilitate better sealing with a battery package.
These and other objects will become apparent from the following description of a preferred embodiment taken together with the accompanying drawings and the appended claims.